This invention relates to a coating composition to protect and lubricate, if desired, the surface of an article without adversely affecting or otherwise degrading the physical properties of the article onto which the coating is applied. More particularly, the present invention relates to such a coating employed as a lubricant and/or wetting agent which can be applied directly onto the surface of a cable, wire or object to be pulled through a conduit, duct, raceway and die to facilitate the joining of two members together such as mounting a pneumatic tire upon a rim or press-fit operation.
While not limited thereto, the coating of the present invention is particularly useful to form a coating of lubricant on wire and/or cable to facilitate pulling operations through a die, conduits and/or ducts. During such pulling operations, the ever-present problem of friction occurs between the outside surface of the object being pulled and the inside surface of the passageway. From an economic standpoint, it is desirable to use the longest possible length of cable or wire during a single pull through the conduit, duct or die. However, as the length of cable or wire involved in a single pull increases, there is a corresponding increase to the necessary pulling force imposed on the cable or wire. If an excessive pulling force is developed, the cable or wire elongates beyond an allowable value causing fractures or breaks to occur. After a cable is drawn into a conduit or raceway, it is frequently necessary to move the cable in a reverse direction to facilitate dressing operations to the surface of the cable sheathing. Back and forth adjustments to the position of cable within a conduit is required when the preselected lengths of cable have their ends pre-equipped with a system of connectors.
In the past, a thixotropic paraffin-based gel, or petroleum-based lubricant was applied by hand onto the surface of the cable preparatory to the pulling operation. An applicator system such as is disclosed in U.S. Pat. No. 4,028,473, eliminated much of the labor and mess usually associated with manual application of the lubricant onto the cable. However, a heavy residue of lubricant remains on the surface of the cable whereby the necessary splicing operations were impeded because of the residue particularly in an underground environment.
Instead of a thixotropic paraffin-based gel or petroleum-based lubricant, there is disclosed in U.S. Pat. No. 3,925,216, a lubricant comprised of polyethylene oxide in an alcohol-water solution. Such a lubricant will eliminate much of the clean-up operations because it provides a desirable property of rapid evaporation. However, this lubricant has inferior friction-reducing properties as compared to a thixotropic gel, particularly in regard to the necessary cable dressing operations and back and forth adjustments of the cable when using selected lengths with pre-prepared connectors. A lubricant of polyethylene oxide in an alcohol-water solution will rapidly evaporate and is highly water-soluble whereby little lubricant, if any, remains after the pulling operation is completed. However, this lubricant composition can be useless or ineffective when the ductwork contains or is filled with water as frequently occurs when the ductwork is underground.
In a wire- or rod-drawing operation, a protective coating is necessary to prevent exposure to oxidizing air and thereby minimizes the formation of scale which quickly wears dies out of shape as well as spoiling the workpiece. Pickling and a water rinse usually precede the drawing operation. Ordinarily, greasy lubricants are ineffective to protect the die because such lubricants do not adhere to an aqueously-wet surface of the workpiece. In the regular wire-drawing practice, the workpiece is coated with the liquor or soap solution just prior to the actual drawing operation by submerging the workpiece in the solution until the workpiece is drawn through the die. Liquor or soap solutions do not form a sufficiently thick lubricant film on the workpiece.